October 31, 1999

By PAUL CHURCHLAND

THE UNDISCOVERED MIND
How the Human Brain Defies Replication, Medication, and Explanation. By John Horgan.
325 pp. New York:
The Free Press. $25.

ohn Horgan is a self-described ''mysterian.'' The mind, he suspects, is an implacable mystery, forever beyond the reach of human science. His new book has two agendas. The first is overt and conventional -- a journalist's overview and evaluation of the various mind-brain sciences. The second is more ambitious -- a philosophical argument that all such sciences are doomed to at least partial failure from the outset. Accordingly, he argues, the current pretensions of science to provide either explanatory understanding or clinical effectiveness should be met with polite skepticism at best and outright derision at worst. Appropriately, a series of lively case studies -- the first agenda -- serves to illustrate and presumably support his second, rather darker one.

And dark it is. Horgan is unable to hide entirely his impatience with almost everything he addresses. But ''The Undiscovered Mind'' is saved from mere crankiness by his light touch (there are some chuckles here), his evenhandedness (almost everybody gets torched) and by the fact that he gets most of his victims straight, or anyway, straight enough for his popular-press purposes. Well, why not? A brief blast by a blowtorch never did stout theory any lasting harm. And there is some satisfaction to be had in watching everyone else's ox being gored, even if one has to endure the goring of one's own.

Horgan begins the book where he is going to end, with the puzzle of how consciousness could ever be explained within the purely physicalist resources of modern neuroscience. Any explanation of mind in terms of matter, he says, almost immediately seems doomed to be missing something. ''Some modern philosophers,'' he says, call this apprehension ''the explanatory gap.''

It's a bad beginning, because the feeling of missing something, however real and urgent, is more likely to signal a mere failure of imagination or comprehension by the beholder than to be a reliable indicator of an objective gap between distinct phenomena in the world. Historical precedents abound. Who could have imagined that light and its manifold objective spectral colors could ever be explained by the arcane theory of traveling oscillations in electric and magnetic fields, of all things? Though they are paradigms of good sense now, such ''reductionist'' theories of light and sound gave people fits at the time, including intelligent people like the philosopher George Berkeley, the poet William Blake and the naturalist (and poet) Johann Wolfgang von Goethe. All of them went to their graves insisting, sometimes eloquently, on the failure of such theories to bridge a similar felt gap. That gap, of course, lay not in the world but entirely in their heads. Horgan forthrightly reports this objection, minus the history lesson, from the mouth of the neuroscientist Patricia Goldman-Rakic. But he is unpersuaded.

His opening suspicions unallayed, he turns to his primary journalistic task. We get an excellent summary of both the rationale and the clinical pretensions of Freudian theory and its repeated failure, under controlled tests, to display any success beyond the well-known placebo effect, an ''effect'' it shares with its equally (in)effective talk-based clinical competitors. This section is fun, for we get a historical peek at Freud the personal scoundrel and a current peek at Freudian analysts agonizing incoherently, at their annual meeting, over the faded fortunes of their dubious craft. But this is beating a dead horse. Mainstream science, if not all therapists, rightly turned its back on Freud decades ago.

Since then, pharmaceuticals such as clozapine, lithium salts and fluoxetine (Prozac) have proved to be at least partly effective, especially for the most devastating forms of mental illness, like schizophrenia, bipolar disorder and major depression, illnesses that Freudian therapists were disinclined to tackle anyway on grounds that they are flatly untreatable. Horgan, however, takes almost as dim a view of these new treatments as he does of psychoanalysis, partly because of their limited effectiveness, partly because of their unwelcome side effects, partly because we understand so poorly why they have the effects they do and partly because of their potential for plain abuse in the form of too-casual prescriptions by overburdened doctors.

These points are salutary, but Horgan's grumpiness is here more puzzling. For better or worse, the insane asylums of the 1940's and 50's are now mostly emptied, thanks to first-generation psychopharmaceuticals. Moreover, second- and third-generation agents are here, and these are more selective in their activity and thus less ham-fisted in their side effects. And research into still better agents is already guided by research into what the normal regime of neurotransmission and reception looks like. Deviations from the desired baseline can thus be chemically identified, and appropriate agents to correct them can be constructed and explored. The situation here is more legitimately hopeful than Horgan portrays. In particular, the assembled constraints on the evaluation of new drugs are stiff and will get stiffer: we can control the relevant experiments and clinical trials much better than with talk-therapy techniques, and we have the comparatively stable authority of chemistry and biology to give reliable structure to our undertakings. Perhaps this is what Horgan is urging on us. And perhaps he's just being censorious. Fair enough. We have a long way to go. In the meantime, we can still do measurable good.

Horgan then turns to studies of the genetic basis of cognitive and emotional disorders. He provides an entirely legitimate critique of the impulse (more common among journalists than scientists) to announce the discovery of ''the gene'' for this, that or the other psychiatric disorder, and he gets in some good kicks at genetic determinism. He fails adequately to explain, however, that genetic effects are not confined to the realm of fetal and childhood development. The genetic materials within our cells exert a continuing regulative effect on most aspects of our adult biochemical economy, our neuronal activities included. Gene expression -- the normal production and regulation of proteins -- is a lifelong matter in all of us. Defects in that regulation can thus be addressed with profit, even in adults. Waving the specter of genetic determinism here, as Horgan does, is mostly missing the point.

Next up is evolutionary psychology, which hopes to explain present cognitive universals in terms of past evolutionary pressures. And last up is classical artificial intelligence, which hopes to re-create cognition in suitably programmed computers. Horgan's critiques are rather better here, although not the best, and I was disappointed to find artificial neural networks described poorly and dismissed summarily, in a single page (a poor ox, but my own).

The fact that consciousness is mysterious to us is a current and perhaps changeable fact about us, not a permanent, heavy-duty metaphysical fact about consciousness itself. Horgan's closing lament wrongly parades our ignorance of consciousness as positive evidence of its transcendent nature. It is no such thing. Moreover, in his discussion of Francis Crick, he wrongly likens the pursuit of a progressive scientific research program to the doctrinal faith of traditional religions. That's just petulant. Science is based on a methodology designed endlessly to produce, evaluate and incorporate significant doctrinal and conceptual change. Horgan has a blind spot in this respect. He sees the enterprise of science as like the writing of a freshman physics exam. You confront, say, 20 questions. You do the easy ones first -- the first 15, perhaps -- and then you are up against the really hard ones. Most likely, they are beyond you. And so science stops.

But it isn't like that. For any puzzling phenomenon, there is an infinity of possible conceptualizations and explanations. Each major success opens a new domain of unseen experimental techniques, and new puzzles to go with them in turn. Running out of addressable problems and candidate theories to explain them is the last thing science needs to worry about. And the nature of mind, at least at the moment, is the last topic that might be in danger of stagnation. Horgan's final take on this is plain defeatist. But if he is weary, let him sit down. The rest of us will go on.

Paul Churchland's most recent books include ''The Engine of Reason, the Seat of the Soul: A Philosophical Journey Into the Brain'' and ''On the Contrary: Critical Essays, 1987-1997.''